Application of the triple porosity model in well–log effectiveness estimation of the carbonate reservoir in Tarim oilfield

In carbonate reservoirs, effectiveness estimation using logging data has great challenges. According to the pore structure characteristics of the fractured and vuggy carbonate reservoir, Aguilera and Aguilera [Roberto F. Aguilera and Roberto Aguilera, 2004. A Triple Porosity Model for Petrophysical Analysis of Naturally Fractured Reservoir, Petrophysics, 45(2):157–166.] presented a triple porosity model, in which the secondary porosity was divided into connected fractured (and/or) vuggy porosity and non-connected vuggy porosity. In this paper, a new technology is presented to determine the values of the different porosity in the triple porosity model. Based on lateral logs responses, we derive analytical equations that contain connected fractured (and/or vuggy) porosity, non-connected vuggy porosity, matrix porosity and so on. Using these equations and the conventional log data, we can obtain the petrophysical parameters, such as connected fractured porosity, non-connected vuggy porosity and so on. Then the connected fractured (and/or vuggy) porosity and its percentage in the total porosity are used to indicate the effectiveness of the carbonate reservoir. This method has been applied for the well log interpretation of the 123 testing intervals from the 52 wells in Tarim oil field. Agreement ratio of the interpretation results is 91%, which verifies the validity of the presented method.